Mixed-mechanism Glaucoma
Chat Highlights
December 3, 2003

Norma Devine, Editor

On Wednesday, December 3, 2003, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Mixed-mechanism Glaucoma."

Moderator:  Dr. Wilson, as you know, we recently discussed combined-mechanism glaucoma; now we would like to discuss mixed-mechanism glaucoma.  What is the difference between them?  

Dr. Rick Wilson:  Combined mechanism glaucoma is usually a combination of open-angle glaucoma with a closed-angle component; mixed-mechanism glaucoma is a combination of two different types of glaucoma.

Moderator:  Like angle closure and open angle?

Dr. Rick Wilson:  Angle-closure glaucoma and open-angle glaucoma would usually mean combined-mechanism glaucoma.  Mixed-mechanism glaucoma might be open-angle glaucoma with a steroid-induced component.

P:  Would a doctor tell me if I had mixed-mechanism glaucoma, or would I need to ask?  

Dr. Rick Wilson:  I would think that your doctor would tell you what kind of glaucoma you have.

P:  Is mixed-mechanism glaucoma usually a result of steroid use and glaucoma?

Dr. Rick Wilson:  "Mixed" just means more than one kind of glaucoma, for example, traumatic and hemorrhagic, open angle and inflammatory, etc.

P:  How common is mixed-mechanism glaucoma?

Dr. Rick Wilson:  It's unusual in a general ophthalmologist's office, but common in a glaucoma specialist's office.

P:  Why is that? 

Dr. Rick Wilson:  Because we see so many referred glaucoma cases, we are much more likely to see the unusual ones.

P:  My medical insurance won't pay for a glaucoma specialist, so I see a general ophthalmologist on a regular basis.  Should I be concerned that he might be missing complex factors in my case?  

Dr. Rick Wilson:  A glaucoma specialist does not charge any more than a general ophthalmologist in most areas of the country, and usually saves money by not subjecting patients to lasers they know won't work, and doing surgery better than general ophthalmologists.  Obviously, I am biased, but feel that glaucoma specialists are really cost effective.  It is hard to answer your question, other than to keep an eye on your visual fields to be sure they are not getting worse.

P:  Can that patient do anything to be referred to a glaucoma specialist in U.S. medical insurance plans?

Dr. Rick Wilson:  That depends a lot upon the plan.  If the patient seems to be getting worse, that should be a serious basis for a consultation with a specialist. 

P:  Does having two components make mixed-mechanism glaucoma harder to diagnose?

Dr. Rick Wilson:  Yes, one kind may predominate and hide the other kind.

P:  Does mixed mechanism result in more than one approach used in treatment?

Dr. Rick Wilson:  Often it does.  If there were an inflammatory component, steroids, not prostaglandins, would usually be used.  

P:  How is an inflammatory glaucoma diagnosed?  Does the inflammation needs to be established for a long time?

Dr. Rick Wilson:  Intraocular pressure is increased in an eye with inflammation.  The inflammation needs to be controlled for the long term or it will do continued damage to the inside of the eye.

P:  What is the prognosis for someone with mixed-mechanism glaucoma?

Dr. Rick Wilson:  That depends entirely upon the kinds of glaucoma that make up the mix.  An inflammatory glaucoma post trauma might progress till no medications were needed, or the inflammation could make a less serious glaucoma very difficult to treat without surgery.

P:  Would ICE (Chandler's) be an example of mixed-mechanism glaucoma?

Dr. Rick Wilson:  No, that would just be the one kind.

P:  According to your definition, I have both combined- and mixed-mechanism glaucoma.  

Dr. Rick Wilson:  Combined-mechanism glaucoma is by definition a mixed-mechanism glaucoma. 

P:  Can treatment of mixed-mechanism glaucoma result in single-mechanism glaucoma?  

Dr. Rick Wilson:  Yes.  Patients with an inflammatory component to their glaucoma could have the inflammation treated, and the glaucoma could become much easier to treat.

P:  I have closed angles and normal-tension glaucoma.  If I start to have visual field defects and optic nerve damage with pressures in the teens, would that be mixed or combined?  

Dr. Rick Wilson:  Closed angle and open angle equal combined.  Most people would probably label closed angle-glaucoma plus normal-tension glaucoma as mixed mechanism.  Remember, these are overlapping terms, so other glaucoma specialists might interpret them differently.

P:  Does it make a difference what it's called as long as it is treated correctly?  

Dr. Rick Wilson:  It helps so that we doctors can talk about problems among ourselves.

P:  How can you tell if there is inflammation in the eye?

Dr. Rick Wilson:  The blood vessels are dilated on the surface of the sclera more than on the conjunctiva.  There is also more serum or protein from the blood leaking into the inflamed eye.  This serum can be seen with the slit lamp by shining a thin beam of light through the fluid of the eye.  If the fluid is totally clear, the beam of light is not seen.  If the fluid is slightly murky with serum leaking into it, you would see the beam like a ray of light going through a smoky room.

Moderator:  Thank you, Dr. Wilson.  

Dr. Rick Wilson:  Thanks for your attention tonight everyone. I won't be here again until the new year, so I want to wish you holidays that are healthy and satisfying.

Moderator:  Happy holidays to you and your family, Dr. Wilson.

End of highlights for December 3, 2003.

On December 10, Dr. Werner discussed "Healthy Lifestyles" in the Chat room. Click here for highlights of that meeting.

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